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A080772 Numbers of numbers <= n having prime factors <= k, triangular array read by rows. +0
1
1, 1, 2, 1, 2, 3, 1, 2, 4, 4, 1, 2, 4, 4, 5, 1, 2, 4, 4, 6, 6, 1, 2, 4, 4, 6, 6, 7, 1, 2, 4, 4, 6, 6, 8, 8, 1, 2, 4, 4, 6, 6, 9, 9, 9, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 11, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 12, 12, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 12, 12, 13, 1, 2, 4, 4 (list; table; graph; listen)
OFFSET

1,3

COMMENT

T(n,k) = #{m: 1<=m<=n and p<=k for prime factors of m}.

FORMULA

T(n, n)=n and T(n, k-1) = if k is prime then k-1 else T(n, k), 1<k<=n.

EXAMPLE

Triangle begins:

................. 1

............... 1...2

............. 1...2...3

........... 1...2...4...4

......... 1...2...4...4...5

....... 1...2...4...4...6...6

..... 1...2...4...4...6...6...7

... 1...2...4...4...6...6...8...8.

CROSSREFS

Sequence in context: A136311 A126260 A163491 this_sequence A145111 A059250 A104795

Adjacent sequences: A080769 A080770 A080771 this_sequence A080773 A080774 A080775

KEYWORD

nonn,tabl

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 10 2003

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.


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